Segment Information - Segment Results and Operating Revenue (Details ) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues by products and services
Revenues	$ 17,478	$ 19,687	$ 20,712
Cost of services and products	7,868	8,488	8,934
Selling, general and administrative	3,078	2,895	3,464
Gain on sale of businesses	(773)	0	0
Loss on disposal groups held for sale	700	0	0
Less: stock-based compensation	(98)	(120)	(175)
Total expense	10,775	11,263	12,223
Total segment adjusted EBITDA	6,703	8,424	8,489
Operating Segments
Operating revenues by products and services
Revenues	17,478	19,687	20,712
Cost of services and products	3,383	3,641	3,862
Selling, general and administrative	1,663	1,717	1,843
Gain on sale of businesses	0
Loss on disposal groups held for sale	0
Less: stock-based compensation	0	0	0
Total expense	5,046	5,358	5,705
Total segment adjusted EBITDA	12,432	14,329	15,007
Operating Segments | Business
Operating revenues by products and services
Revenues	13,039	14,119	14,808
Cost of services and products	3,260	3,488	3,661
Selling, general and administrative	1,101	1,178	1,262
Gain on sale of businesses	0
Loss on disposal groups held for sale	0
Less: stock-based compensation	0	0	0
Total expense	4,361	4,666	4,923
Total segment adjusted EBITDA	8,678	9,453	9,885
Operating Segments | Mass Markets
Operating revenues by products and services
Revenues	4,439	5,568	5,904
Cost of services and products	123	153	201
Selling, general and administrative	562	539	581
Gain on sale of businesses	0
Loss on disposal groups held for sale	0
Less: stock-based compensation	0	0	0
Total expense	685	692	782
Total segment adjusted EBITDA	3,754	4,876	5,122
Operations and Other
Operating revenues by products and services
Revenues	0	0	0
Cost of services and products	4,485	4,847	5,072
Selling, general and administrative	1,415	1,178	1,621
Gain on sale of businesses	(773)
Loss on disposal groups held for sale	700
Less: stock-based compensation	(98)	(120)	(175)
Total expense	5,729	5,905	6,518
Total segment adjusted EBITDA	$ (5,729)	$ (5,905)	$ (6,518)